CVE-2026-97058 in sprintf-js
Summary
by MITRE • 09/24/2026
sprintf-js through 1.1.3 passes unbounded precision specifiers to toFixed, toExponential, and toPrecision methods without validation, causing uncaught RangeError exceptions. Attackers who control format strings can inject precision values exceeding ECMAScript limits to abort calling operations with minimal payload.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/24/2026
The vulnerability identified in sprintf-js versions through 1.1.3 stems from a critical input validation failure within the library's string formatting logic, specifically affecting numeric conversion methods such as toFixed, toExponential, and toPrecision. These JavaScript native methods are designed to format numbers into strings with specific decimal precision or exponential notation limits defined by the ECMAScript standard. However, sprintf-js acts as an intermediary that accepts user-supplied format specifiers without adequately sanitizing the precision arguments before passing them to these underlying engine functions. This architectural oversight allows attackers who have control over the input format string to inject arbitrary numeric values for precision parameters, bypassing any internal bounds checking mechanisms that should restrict inputs to valid ECMAScript ranges.
From a technical perspective, this flaw represents a classic case of improper validation of user-supplied data leading to uncaught exceptions. When an attacker provides a precision value that exceeds the maximum limit allowed by the JavaScript engine for these specific methods, the runtime environment throws a RangeError exception. Because sprintf-js does not catch or handle this error internally during its execution flow, the exception propagates up the call stack and terminates the current operation abruptly. This behavior effectively transforms what might otherwise be a simple string formatting task into a vector for denial of service attacks against applications relying on this library for dynamic text generation.
The operational impact of this vulnerability is primarily centered around availability rather than confidentiality or integrity, although it can serve as an initial foothold in more complex attack chains. By triggering uncaught exceptions, attackers can cause web servers running Node.js to crash if the error handling at a higher level does not gracefully recover from such runtime faults. In server-side applications, this could lead to service disruption for legitimate users or force the application into an unstable state requiring manual intervention or restart. Furthermore, in client-side contexts, it may result in broken user interfaces or failed form submissions where dynamic content generation is expected, degrading the overall user experience and potentially exposing backend logic if error messages are leaked back to the client with stack traces.
This vulnerability aligns closely with CWE-20 Improper Input Validation, as the core issue lies in the failure to verify that input data conforms to expected constraints before processing. Additionally, it maps to ATT&CK technique T1498 Network Denial of Service, specifically under sub-techniques involving resource exhaustion or service disruption through application-level flaws rather than network flooding. The ability to crash a process with minimal payload size makes this particularly dangerous in high-throughput environments where such formatting operations are frequent and automated.
Mitigation strategies for this vulnerability involve immediate upgrading to patched versions of sprintf-js that implement strict bounds checking on precision arguments before they reach native JavaScript methods. Developers should also consider implementing defensive coding practices by wrapping critical string formatting calls in try-catch blocks to handle potential RangeErrors gracefully, ensuring that the application can recover from unexpected input without crashing. Furthermore, adopting a principle of least privilege for library dependencies and regularly auditing third-party packages for known vulnerabilities is essential to maintaining robust security posture against such logic-based denial of service vectors.